In modern internal combustion engines, devices for variably setting the control times of gas exchange valves are used so that the phase relation between crankshaft and camshaft can be set variably, within a defined angular range, between a maximum advanced position and a maximum retarded position. The device is integrated into a drive train, by which torque is transferred from the crankshaft to the camshaft. This drive train may be implemented, for example, as a bolt, chain or gearwheel drive. Furthermore, the device is connected fixedly in rotation to a camshaft and has one or more pressure chambers, by means of which the phase relation between the crankshaft and camshaft can be varied in a directed manner. Conventionally, the devices are designed as pivoting motors of the vane cell type of construction, a cellular wheel being driven by the crankshaft and an impeller being connected fixedly in terms of rotation to the camshaft. In this case, the cellular wheel and the impeller form pressure chambers acting counter to one another. By the pressure medium being supplied to one group of pressure chambers, while at the same time pressure medium is discharged from the other group of pressure chambers, the phase relation of the impeller with respect to the cellular wheel and therefore of the camshaft with respect to the crankshaft can be set variably.
A device of this type is known, for example from U.S. Pat. No. 6,457,447 B1. The device has a cellular wheel, an impeller and a side cover, the cellular wheel being drive-connected to a crankshaft and the driven element being fastened fixedly in terms of rotation to a camshaft.
The cellular wheel is of pot-shaped design and has a cylindrical circumferential wall and a disk-shaped sealing cover which extends from the circumferential wall radially inward. Furthermore, the cellular wheel has a plurality of projections. The projections extend from the circumferential wall radially inward and from the sealing cover in the axial direction.
Within the pot-shaped structure is arranged the impeller which has an essentially cylindrically designed hub element and a plurality of vanes extending outward in the radial direction.
A side cover is arranged on the open side of the pot-shaped cellular wheel and is screwed to the latter. A plurality of pressure spaces are thus formed in the device and are delimited in the radial direction by the impeller and the circumferential wall, in the circumferential direction by adjacent projections and in the axial direction by the sealing cover and the side cover. A vane of the impeller extends into each of the pressure spaces, with the result that each of the pressure spaces is divided into two pressure chambers acting counter to one another.
Via a chain wheel which is formed on the side cover, the device is driven by the crankshaft by means of a chain drive while the internal combustion engine is in operation. By pressure be supplied to one group of pressure chambers, while at the same time pressure medium is discharged from the other pressure chambers, the phase position of the impeller with respect to the cellular wheel can be set variably.